1. Field of the Invention
The present invention relates to endosteal fixation of a ligament by device insertion and, more specifically, to methods and devices for bicortical tibial fixation of anterior cruciate ligament grafts.
2. Description of the Related Art
When a ligament becomes detached from a bone, surgery usually is required to reconstruct the ligament. Often, a substitute ligament or graft is secured into bone tunnels to facilitate incorporation and permanent attachment.
Various methods of graft attachment are known, including the use of interference screws to secure the graft against the walls of a tunnel drilled through the tibia and a socket formed in the femur. A strong graft attachment is obtained by using a metal interference screw to wedge a graft bone block to the wall of a graft tunnel formed through the bone, as disclosed in U.S. Pat. No. 5,211,647 to Schmieding. If a bioabsorbable interference screw is used, the graft can be wedged directly against the bone by the screw, without a bone component.
In either case, the graft usually is secured as close as possible to the normal ligament origin and insertion site, which are at the top of the tibial tunnel (the tibial plateau) and the entrance to the femoral socket in ACL reconstructions. The portion of the graft extending out the bottom of the tibia is ordinarily secured to the outside of the bone with a staple or using screw/washer fixation.
The above-described secondary fixation of the graft to the exterior surface of the tibia is disadvantageous in that it is subject to abrasion from external elements, and is generally less secure than internal fixation. Accordingly, a graft fixation technique is needed which provides increased fixation strength of the graft in the tibial tunnel, and improved healing of the tibial tunnel and associated tissue.